I came through Heathrow T3 at lunch time yesterday (Fri 24th Sept). (before the outage). Through the e-gates in 5 minutes.
If you don't have a biometric passport or you're traveling with children under 12, then you need to be seen by a BF person.
I have been using LHR all pandemic. The longest wait was about 45 minutes.
(The longest queue was at London City, no e-gates).
Yes, I have been "lucky" and have missed the epic queues.
Most arrivals from "red zone" countries are being routed through T4 at LHR so that keeps it simple.
Therefore, assuming no e-gate outage and you have a biometric passport and your PLF filled out (linked to passport), not been near a red zone country, double jabbed, then you should have little to no delay entering the UK.